The article is devoted to a systematic analysis of fixations of messages about astronomical phenomena in the Novgorod chronicles with the use of the data - base “Chronology of the Novgorod Chronicles IXth - mid- XVth Centuries” The dates of astronomical phenomena recorded in the chronicles, can serve as the absolute dates, and be the basis for the reconstruction of time counting systems of the Novgorod chronicles. This idea is supported by the identification of the Byzantine- Bulgarian chronology in the initial Russian chronicle, which is better preserved in the Novgorod-Sophian group of chronicles. The article traces some regularity in the fixation of astronomical phenomena, as well as in separate groups of chronicles and in centuries. Observation is given to some possible correlation between the change of the chroniclers and their interest in the subject. It is concluded that the use of database technology can detect hitherto little explored potential of Novgorod chronicles as historical sources, and to disclose their additional information capabilities.